diff --git a/pkgs/development/python-modules/dukpy/default.nix b/pkgs/development/python-modules/dukpy/default.nix
index 453d68e8534e9..7b684658d0f71 100644
--- a/pkgs/development/python-modules/dukpy/default.nix
+++ b/pkgs/development/python-modules/dukpy/default.nix
@@ -21,6 +21,12 @@ buildPythonPackage rec {
     hash = "sha256-8RDMz9SfBoUe7LQ9/atsZlJ/2uwLUb0hZxeYdsUOGpU=";
   };
 
+  postPatch = ''
+    substituteInPlace tests/test_webassets_filter.py \
+      --replace-fail "class PyTestTemp" "class _Temp" \
+      --replace-fail "PyTestTemp" "Temp"
+  '';
+
   build-system = [ setuptools ];
 
   dependencies = [ mutf8 ];